I just had my first interaction with the new Leader and Clerk Resources update on LDS.org.

I've noticed that the Elder's Quorum President position no longer has a "Manage Callings" option. However, Sunday School President still has this option. While the Sunday School President cannot call (typically) SS teachers in his organization, the EQ President can extend callings and perform those ordinations within his quorum (with permission of the Bishop). Was this an error or was there a reason for removing this feature from EQ Presidents?

You have multiple callings and need to switch roles. If you look at the top right of the LCR page, you will see a drop list highlighted in yellow that says "Sunday School President." Click on that and change it to "Elders Quorum President."